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<a name="Range-checks-on-poly_005fints"></a>
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<a name="Range-checks-on-poly_005fints-1"></a>
<h4 class="subsection">10.3.6 Range checks on <code>poly_int</code>s</h4>

<p>As well as the core comparisons
(see <a href="Comparison-functions-for-poly_005fint.html#Comparison-functions-for-poly_005fint">Comparison functions for <code>poly_int</code></a>), <code>poly_int</code> provides
utilities for various kinds of range check.  In each case the range
is represented by a start position and a size rather than a start
position and an end position; this is because the former is used
much more often than the latter in GCC.  Also, the sizes can be
-1 (or all ones for unsigned sizes) to indicate a range with a known
start position but an unknown size.  All other sizes must be nonnegative.
A range of size 0 does not contain anything or overlap anything.
</p>
<dl compact="compact">
<dt>&lsquo;<samp>known_size_p (<var>size</var>)</samp>&rsquo;</dt>
<dd><p>Return true if <var>size</var> represents a known range size, false if it
is -1 or all ones (for signed and unsigned types respectively).
</p>
</dd>
<dt>&lsquo;<samp>ranges_maybe_overlap_p (<var>pos1</var>, <var>size1</var>, <var>pos2</var>, <var>size2</var>)</samp>&rsquo;</dt>
<dd><p>Return true if the range described by <var>pos1</var> and <var>size1</var> <em>might</em>
overlap the range described by <var>pos2</var> and <var>size2</var> (in other words,
return true if we cannot prove that the ranges are disjoint).
</p>
</dd>
<dt>&lsquo;<samp>ranges_known_overlap_p (<var>pos1</var>, <var>size1</var>, <var>pos2</var>, <var>size2</var>)</samp>&rsquo;</dt>
<dd><p>Return true if the range described by <var>pos1</var> and <var>size1</var> is known to
overlap the range described by <var>pos2</var> and <var>size2</var>.
</p>
</dd>
<dt>&lsquo;<samp>known_subrange_p (<var>pos1</var>, <var>size1</var>, <var>pos2</var>, <var>size2</var>)</samp>&rsquo;</dt>
<dd><p>Return true if the range described by <var>pos1</var> and <var>size1</var> is known to
be contained in the range described by <var>pos2</var> and <var>size2</var>.
</p>
</dd>
<dt>&lsquo;<samp>maybe_in_range_p (<var>value</var>, <var>pos</var>, <var>size</var>)</samp>&rsquo;</dt>
<dd><p>Return true if <var>value</var> <em>might</em> be in the range described by
<var>pos</var> and <var>size</var> (in other words, return true if we cannot
prove that <var>value</var> is outside that range).
</p>
</dd>
<dt>&lsquo;<samp>known_in_range_p (<var>value</var>, <var>pos</var>, <var>size</var>)</samp>&rsquo;</dt>
<dd><p>Return true if <var>value</var> is known to be in the range described
by <var>pos</var> and <var>size</var>.
</p>
</dd>
<dt>&lsquo;<samp>endpoint_representable_p (<var>pos</var>, <var>size</var>)</samp>&rsquo;</dt>
<dd><p>Return true if the range described by <var>pos</var> and <var>size</var> is
open-ended or if the endpoint (<var>pos</var> + <var>size</var>) is representable
in the same type as <var>pos</var> and <var>size</var>.  The function returns false
if adding <var>size</var> to <var>pos</var> makes conceptual sense but could overflow.
</p></dd>
</dl>

<p>There is also a <code>poly_int</code> version of the <code>IN_RANGE_P</code> macro:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>coeffs_in_range_p (<var>x</var>, <var>lower</var>, <var>upper</var>)</samp>&rsquo;</dt>
<dd><p>Return true if every coefficient of <var>x</var> is in the inclusive range
[<var>lower</var>, <var>upper</var>].  This function can be useful when testing
whether an operation would cause the values of coefficients to
overflow.
</p>
<p>Note that the function does not indicate whether <var>x</var> itself is in the
given range.  <var>x</var> can be either a constant or a <code>poly_int</code>.
</p></dd>
</dl>

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